Gear-cutting machine.



Patented Augwl1 1914.

J. GRUNDSTEIN.

GEAR CUTTING MAOHINE.

J. GRUNDSTEIN.

GEAR CUTTING MACHINE.

APPLwA'noN FILED 11111.27, 1014.

1, 1 05,649. Patented Aug. 4, 1914.

4 SHEETS-SHEET 2.

J. GRUNDSTEIN.

GEAR CUTTING MACHINE.

APPLICATION IILBD JAN.27,1914. 1,1 Patented Allg. 4, 1914.

J. GRUNDSTEIN.

GEAR CUTTING MACHINE.

APPLICATION FILED JAN.27,1914.

Patented Aug. 4, 1914.

4 SHEETS-SHEET 4.

un sra'rns Parana neuron.

K JULIUS GRUNDSTEIN, F ETTLINGEN, GERMANY, ASSIGNORTO MASCHINENFABRIK LORENZ, OF ETTLINGEN, GERMANY, A FIRM.

GEAR-CUTTING MACHINE.

Specification of Letters Patent. 13317911156@ Aug, 4, 1914. Application led January 27, 1914. Serial No. 814,731.

To all whom it may concern Be it known that I, J UIJUS GRUNDSTEIN, a subject of the Emperor of Russia, residing at Ettlingen, Grand Duchy of Baden, in the German Empire, have invented certain new and useful Improvements in Gear-Cutting Machines, of which the following is a full, clear, and exact description.

' In ordinary gear cutting machines Working by the method of cutting gear teeth by helicoidal cutter, a worm dividing wheel is firmly connected with the table to which the Work or blank is fixed. This dividing worm wheel is driven and transmits its rotation to the table. This rotation corresponds to the division which it is desired to give to the gear-Wheel to be milled. This well known arrangement has the disadvantage that any faults in the worm wheel, that is to say, in the dividing wheel, which cannot be avoided, are always transmitted to the same points of the work secured to the table connected with the dividing wheel, that is to say, the faults of the dividing wheel are copied in such a 'manner that each tooth milled shows throughout theI whole of its` Width the same fault of thc dividing wheel. This disadvantage is obviated according to this invention which attempts to transmit each fault of the dividing wheel at cach revolution to a different tooth of the blank. Each 'fault of the dividing wheel is not to be always transmitted over and over again to the same tooth of the work or blank7 but is distributed over the whole circumference of the latter. Owing to the method of cutting gear teeth by helicoidal cutter, each single fault of the dividing wheel travels in a spiral around the whole circumference of the work. Each milled tooth of the work shows therefore throughout the whole of its Width different faults of the dividing wheel, so that each face of the tooth, over the whole width of the tooth, consists of a continuous series of positive and negative faults l relatively to the theoretically correct division. The faults themselves are moreover smaller at each point of the blank than the corresponding faults of the dividing wheel. This problem is solved according to this invention by `producing the dividing movement of the blank, not by one dividing wheel firmly secured to it, but b two such wheels loosely mounted on the ta le supporting the work or blank7 and driven in the same direc- 'means of special toothed rims.

tion by separate worms to which however motion is imparted from a common driving shaft. The rotation ofv these two dividing Wheels which are given unequal angular velocitnies, either owing to the fact that the driving Worms have an unequal number of revolutions or owing o the number of teeth of the dividing wheels being different, or owing to both these facts, is transmitted to the table by intermediate wheels or pairs of intermediate wheels mounted to the table and engaging with the dividing wheels by The angular speed of the intermediate wheels or pairs of intermediate wheels is the aritlimetical mean of the angular velocities of the two dividing wheels, and the faults of the dividing motion are thus' reduced before being transmitted to the circumference of the blank.

A construction according to this invention 1s diagrammatically illustrated in the accompanying drawings.

Figure ly shows a rrear wheel milling machine according to this invention, working by the method of cutting gear teeth by helicoidal cutter or worm hob, in side elevation, Fig. 2 is a plan, Fig. 3 is a vertical section, on an enlarged scale, thrcmgh the lower part of the table and the two dividing wheels. Fig. 4 is a similar view to Fig. 3 and shows a somewhat modified construction for transmitting the. rotation of the dividing wheels to the table. Fig. 5 is a diagram illustrating the movement of the dividing wheels and of the table relatively to each other.

Similar letters refer to similar parts throughout the several views.

The dividing device and its driving gear areal-ranged 1n well known manner in the bed a of the gear cuttinff machine while a stand b which may be adjusted to suit the diameter of the work or blank lw carries the milling cutter c on a carriage movable in the vertical direction.

The foot o" of the table d (Fig. 3) carrying `the yblank w, is rotatably mounted in the bed of the machine. The foot'al1l is provided with an annular flange (l2 carrying at the edge a series of loose intermediate wheels c or of pairs of intermediate wheels f )"1 (Fig. ll). Above and below the annular flange d2, on the foot d1 of the table are mounted loosely worm'wlieels g and L forming each a dividing wheel, the said wheels being7 romediate wheels f and f1 (F ig. 4). v

tated in the same direction by the worms z and 7c. rlhe upper worm wheel g is pro- `vided with a toothed rim g1, and the lower The two Worms z and 7c are driven by means of bevel wheels m and n and spur wheels 0 and p fromone and the same shaft rlFhe driving ofthe said shaft and of the milling cutter is effected in a well known manner from one and the same source of power (for instance a pulley or electric motor).

The movements of the milling cutter and the revolutions of the shaft g and therefore of the dividing gear are adjustable in the known manner by means of change wheels.

rllhe wheels g and 7i rotatedby the worms 'z' and kin the same direction, transmit their' movement through the intermediate wheels e or pairs of intermediate-wheels f f1 to the annular flange Z2 and through the latter, asl

dividing movement, to the table and to the blank secured thereto. As the wheels g and L owing to their inequality and to the inequality of the wormsz' and 7c or of their number of revolutions, run with different angular velocities, the table and therefore the blank is given an angular speed which is they arithmetical mean of the angular speeds of the two driving dividing wheels g and h. In that-way, the unavoidable faults of the wheels g and z. are distributed in a spiral manner over the whole circumference of the blank. Each milled flank or face of the tooth is therefore given a series of different division faults, the resultantvof which approximates to. theoretically exact division. The faults of division themselves are at the single points of each milled flank equal to half the sum of the two faults which coincide at the same moment on the driving dividing wheels.

From the diagram of the movement of the two wheels g and h and of the annular flange ybeing connected byy means of d2 shown in Fig. 5, it follows directly that the largest fault z in the toothed wheel produced is, at the highest, equal to the greatest fault -l- :u or -ly of the two dividing wheels. This most unfavorable case can only take place when' the largest faults w and y of the two dividing wheels are equally great and coincide intime, for in that case half the sum of the twodivision faults a: and i is equal to the greatest fault a in the divi ing wheels. In any other positions of the two dividing wheels, the resultant fault is smaller than the greatest fault in one of the said two wheels. f

I claim:

1. ln a machine vfor cuttmg` gear teeth by a helicoidal cutter, a rotatable table, a device for transmitting the dividing movement to the table, which device consists oftwo dividing worm wheels loosely mounted on the table, and rotatable in the same direction but' with different .angular velocities, two. worms meshing with said worm wheels and to which motion is imparted from a common driving shaft, the said dividing wormwheels special toothed rims and intermediate gearing mounted on the table.

2. ln a machine for cutting gear teeth by a helicoidal cutter, a rotatable blank-holding table, a pair of dividin worm wheels rotatably mounted on the ta le, a worm for driving each dividing worm wheel, common driving means for thev two worms, and means connecting the dividing wheels to each other and to the table whereby the table and therefore the blank is given an angular speed which is the arithmetical mean of the angular speed of the two dividing worm wheels, for the purpose set forth.

Signed a Mannheim this 2nd day of December A. D. 1913 in the presence of two witnesses.

JULIUS GRUNDSTEN. [L. s.]

Witnesses SAMUEL SHoLEs BERGER, C. ll?. HINGE, Jr. 

